Numerous studies have demonstrated that both the risk of coronary heart disease (CHD) in humans and the severity of experimental atherosclerosis in animals are inversely correlated with serum HDL cholesterol (HDL-C) concentrations (Russ et al., Am. J. Med., 11 (1951) 480-483; Gofman et al. Circulation, 34 (1966), 679-697; Miller and Miller, Lancet, 1 (1975), 16-19; Gordon et al., Circulation, 79 (1989), 8-15; Stampfer et al., N. Engl. J. Med., 325 (1991), 373-381; Badimon et al., Lab. Invest., 60 (1989), 455-461). Atherosclerosis is the process of accumulation of cholesterol within the arterial wall which results in the occlusion, or stenosis, of coronary and cerebral arterial vessels and subsequent myocardial infarction and stroke. Angiographic studies have shown that elevated levels of some HDL particles in humans appear to be correlated to a decreased number of sites of stenosis in the coronary arteries of humans (Miller et al., Br. Med. J., 282 (1981), 1741-1744).
There are several mechanisms by which HDL may protect against the progression of atherosclerosis. Studies in vitro have shown that HDL is capable of removing cholesterol from cells (Picardo et al., Arteriosclerosis, 6 (1986), 434-441). Data of this nature suggest that one antiatherogenic property of HDL may lie in its ability to deplete tissue of excess free cholesterol and eventually lead to the delivery of this cholesterol to the liver (Glomset, J. Lipi Res., 9 (1968), 155-167). This has been supported by experiments showing efficient transfer of cholesterol from HDL to the liver (Glass et al., J. Biol. Chem., 258 (1983), 7161-7167; McKinnon et al., J. Biol. Chem., 261 (1986), 2548-2552). In addition, HDL may serve as a reservoir in the circulation for apoproteins necessary for the rapid metabolism of triglyceride-rich lipoproteins (Grow and Fried, J. Biol. Chem., 253, (1978), 1834-1841; Lagocki and Scanu, J. Biol. Chem., 255 (1980), 3701-3706; Schaefer et al., J. Lipid Res., 23 (1982), 1259-1273). More recently, as a possible mechanism for protection against the development of atherosclerosis, Cockerill et. al. (Arterioscler., Thromb., Vasc. Biol, 15, (1995), 1987-1994) have demonstrated that plasma HDL's inhibit the cytokine-induced expression of endothelial cell adhesion molecules (VCAM-1 and ICAM-1) in a concentration dependent and cell specific manner. Accordingly, it is believed that agents which increase HDL cholesterol concentration would be of utility as anti-atherosclerotic agents, useful particularly in the treatment of dyslipoproteinimias and coronary heart disease.
Ureas, thioureas and derivatives thereof are known to be useful for the treatment of various conditions. For example, the use of urea and thiourea derivatives as tyrosine kinase inhibitors, to inhibit cell proliferation and differentiation in the treatment of cancer is disclosed in WO 9640673-A1. The use of [(alkoxy) pyridinyl] amino derivatives to inhibit the secretion of gastric acid is disclosed in WO-9315055. N-phenyl thiourea derivatives and their use in the treatment of atherosclerosis is disclosed in CA-2072704. The use of bis-aryl ureas and related compounds as cardiovascular agents is disclosed in CA-2132771, while the administration of ureas and thioureas for the treatment of ischaemia, asthma, Parkinson's disease, epilepsy, and urinary incontinence is disclosed in U.S. Pat. No. 5,547,966. Substituted thioureas and isothioureas are-also disclosed in U.S. Pat. No. 5,185,358.
The treatment of atherosclerosis with certain ureas, thioureas and derivatives thereof has been suggested in Japanese Patent 83-01841 (the use of ureas and thioureas as inhibitors of squalene epoxidase); U.S. Pat. No. 4,623,662 (the use of certain urea and thiourea compounds to lower serum lipids in warm-blooded animals); and U.S. Pat. Nos. 4,387,105 and 4,387,106 (the use of di(aralkyl) ureas and di(aralkyl) thioureas to inhibit fatty acyl CoA: cholesterol acyl transferase). However, the treatment of atherosclerosis, and the related cardiovascular disease and dyslipoproteinemias, through the elevation of serum HDL cholesterol concentrations with the present urea and thiourea derivatives, has heretofore not been recognized.